Update date field

[stephanevial]

Hello, I would like to update 2 fields date based on a given date. I
have a table with 3 boxes. The operation date is the second field. I
would like to insert given date -1 day for the upper row on the table
and given date +1 day for the bottom row.

Exemple :

row 1 : January 12 (Automatic update - row 2 minus 1 day)

row 2 : January 13 (manually entered)

row 3 : January 14 (Automatic update - row 2 plus 1 day)

Thanks for your help

Stephane